Spark plug



April 21, 1936. I F. A. CARTER ET AL 2,037,851

SAPARK PLUG Filed May 51, 1935 [nvenlons F (/7 Cakfar F I did flm Allomey Patented Apr. 21, 1936 UNETED STATES SPARK PLUG Frank A. Carterand Frank J. McAvoy, Roselle Park, N. J.

Application May 31, 1935, Serial No. 24,407

Claims.

This invention relates to an improved spark plug, has primary referenceto spark intensifying means for said plug, and in particular relates toan intensifier unit in the nature of an attachment susceptible of beingapplied to a conventional marketed type of plug such as is now commonlyused.

By way of introduction and without attempting to attach emphasis orimportance to the attachment idea of the invention, we would like topoint out that the inventive conception comprehends the adoption and useof spark intensifying means which embodies a new basic principle ofoperation in that it serves to provide a spark gap at the time ofinitial starting of the motor when the motor and plug is cold andautomatically throws said plug intensifying gap out of play as soon asthe motor becomes heated to a predetermined degree.

2 Needless to say, we are aware that spark intensifying devices forspark plugs are not new. Generally stated it would appear that the priorart shows many different types of intensifiers most of which are of thepermanent type al- 25 though some adjustable features are incorportedtherein. That is to say, the customary structure with which we arefamiliar includes a sectional electrode wherein a space is maintainedpermanently between the electrode sections to provide a spark gap be itadjustable or not.

We deem it logical to also say that temperature variable sparkintensifying means in the spark plug construction is also not'new. Forex- 35 3 ample, in a patent to one W. P. Kerrigan 1,484,335 of February19, 1924 there is provided a spark plug having in combination with itsspark gap a supplemental spark intensifying gap and electricallyconducting thermostatically op- 40 *1 erating means arranged to bridgethe gap wherein said means is arranged to automatically break thetemporary connection between the electrode end when the plug becomesheated.

By way of contrast with this prior patent 45 which may be utilized as aconvenient guide to introduction of the novelty which we claim, it is tobe noted that we have evolved and produced a structure which involves anabsolutely reverse principle and arrangement. Or stated otherwise,

50 We have perfected a spark intensifier utilizing a supplementaryelectrode element, and a thermostatically controlled contacting elementof a relatively movable type wherein said latter element is in the formof a normally expansible coiled 55 spring with its contact end spacedaway from the adjacent element so long as the plug and engine is cold,but serves to automatically close the'gap and keep it closed when themotor becomes heated, whereby to permit the plug to operate as thoughthe intensifier were not pres- 5 ent.

The particular manner in which this is accomplished will become morereadily apparent from the following description and the accompanyingillustrative pictorial drawing.

In the drawing wherein like numerals are employed to designate likeparts throughout the same:

Figure 1 is a View partly in section and partly in elevation showing theconventional plug with the intensifier unit or attachment appliedthereto.

Figure 2 is a top plan view with the terminal returning or clamping nutremoved to disclose the details of the attachment.

Figure 3 is a sectiona1 view illustrating the parts a little more indetail.

Referring now to the drawing by distinguishing numerals it will beobserved that the conventional spark plug is denoted by the numeral 4and this includes the usual insulating body 5, the retention fitting 6,the central electrode terminating in a contact I cooperable with thecustomary L-shaped spark gap contact 8.

Ordinarily, the upper end of the electrode, that substitute theattachment for the usual clamping nut but also use a similar clampingnut H to hold the terminal or current conductor wire (not shown) inplace. The attachment or unit comprises a suitable insulating base ordevice 12 having a screw-threaded bushing l3 fitted into the socketportion thereof said bushing being connectible with the screw threadedend 9 of the electrode. The laterally directed end M of thesupplementary external contact element I5 is imbedded in the insulationl2 and electrically connected with the bushing l3 and thereforeelectrically joined to the electrode 9. The wire connecting elementcomprises a disk-like head l6 secured by suitable fasteners I! to theinsulator l2 and this is provided with a screw threaded shank or stud I8to accommodate the wire or terminal clamping nut H. The currentconductor means to carry the current from the stud l8 to the electrode 9comprises the aforesaid L-shaped contact l5 and the complemental coiledspring I9. This coiled spring is anchored at one end as indicated at 20in Figure 2 in the insulator 12. This laterally anchored end, however,has electrical connection with the disk I6. The free end of the outerconvoluion of the coil, that is the convolution 2| terminates in alaterally directed element 22 which may be conveniently described as amovable contact and this is cooperable with the stationary contact I5.So long as the plug is. cold, this thermostatic coil spring expandsunder its natural inherent resiliency and provides a spark gap as shownin Figure 4. When the motor reaches a predetermined point of heat themetal expands and closes the gap thereby the current flows steadilythrough the electrode as though the intensifier attachment were notpresent.

With our attachment it is obvious that the gap closes with a few degreesrise in temperature and remains closed so long as the motor is inmotion, thereby making it possible to adjust spark plug points to thebest running gap. In most motors the best results are obtained when thegap in the plug is .028. But when the motor is cold it is difficult tostart and in some of the high compression type motors it is extremelydifficult to start. Our invention completely overcomes the likelihood ofthe motor not starting when it is cold, for it provides the desiredspark intensifying 'gap at this particular period in starting. When,

however the motor becomes heated and this amplified spark isunnecessary, the intensifier automatically goes ofi so to speak since itis not needed during the normal running of the motor. That it ispossible to adjust the device in such a manner that one can obtain anyof the results now claimed on most all intensified plugs. For instance,if a permanent gap is desired move part l5 far enough away from 22 tocause spark to jump to next coil on 2!, which in any case is never morethan .030. If no intensification is desired, press i5 to and against 22.If no intensification spark is desired in starting cold motor and isdesired after motor is warm, move 15 to opposite side of 22.

It is thought that persons skilled in the art to which the inventionrelates will be able to obtain a clear understanding of the inventionafter considering the description in connection with the drawing.Therefore, a more lengthy description is regarded as unnecessary.

Minor changes in shape, size and rearrangement of details coming withinthe field of invention claimed may be resorted to in actual practice, ifdesired.

Having thus described the invention, what is claimed as new is:

1. A spark plug comprising an insulator having an electrode extendingtherethrough, a fitting connected with said insulator, complementalspark points cooperable with the fitting and electrode in the customarymanner, and spark intensifying means associated with said electrode,said intensifying means being of a thermostatically controlled type andbeing normally open to provide an additional spark gap when the plug andmotor is cold, and closed and retained closed as soon as the temperatureof the plug rises to a predetermined degree.

2. As a new article of manufacture, an intensifier attachmentconnectible with the screw threaded end of the electrode in aconventional spark plug comprising an insulator provided with a currentconducting element of a stationary type connectible with said electrode,terminal connector means, and a thermostatically controlled currentconductor element electrically connected with said terminal connectormeans and associated with said current conducting element in theinsulator and normally spaced therefrom to provide an intensifying gapwhen the metal is cold, and automatically movable into closingengagement with said contact when the metal is heated.

3. A spark plug including customary point and electrode and assemblingmeans therefor, and an accessible externally arranged spark intensifyingdevice cooperable with the electrode and including terminal connectormeans and electrically conducting thermostatically operated means.

l. A spark plug including customary point and electrode and assemblingmeans therefor, and an accessible externally arranged spark intensifyingdevice cooperable with the electrode and including terminal connectormeans and electrically conducting thermostatically operated means, saidlast named means embodying a stationary rigid cont-act member and acomplemental coiled spring, the inherent resiliency of said springserving to normally separate the end of the spring from the contactelement to provide a limited spark gap, said spring being acted on by apredetermined degree of heat toautomatically close the spark gap and tokeep it closed during the running of the motor.

5. A spark intensifying attachment of the class described comprising aninsulator provided with a socket having a metallic bushing fittedtherein and screw threaded to fit on the customary electrode, terminalwire attaching means mounted on said insulator, a themostaticallycontrolled electricity conducting coiled spring carried by theinsulator, electrically connected with said terminal connector means andhaving a laterally directed free end portion, a substantially L-shapedcurrent conducting element rigidly imbedded in said insulator and havingits inner end connected with said bushing and having its outer endexposed and cooperable with the free end of said spring.

FRANK A. CARTER. FRANK J. MCAVOY.

